Tape head having sub-ambient channel and methods of manufacture

ABSTRACT

An apparatus according to one embodiment includes a module having a tape bearing surface, an array of magnetic transducers, and a channel in the tape bearing surface. The channel has a longitudinal axis oriented about parallel to a longitudinal axis of the array of magnetic transducers for inducing tenting of a moving magnetic recording tape above the array of magnetic transducers. A method according to one embodiment includes forming a channel in a tape bearing surface of a module. The channel is formed to have a longitudinal axis about parallel to a longitudinal axis of an array of magnetic transducers. The channel is formed proximate to the array of magnetic transducers for inducing tenting of a moving magnetic recording tape above the array of magnetic transducers.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to magnetic tape heads.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

SUMMARY

An apparatus according to one embodiment includes a module having a tapebearing surface, an array of magnetic transducers, and a channel in thetape bearing surface. The channel has a longitudinal axis oriented aboutparallel to a longitudinal axis of the array of magnetic transducers forinducing tenting of a moving magnetic recording tape above the array ofmagnetic transducers.

An apparatus according to another embodiment includes a module having atape bearing surface and an array of magnetic transducers. A firstchannel having a longitudinal axis oriented about parallel to alongitudinal axis of the array of magnetic transducers is present forinducing tenting of a moving magnetic recording tape above the array ofmagnetic transducers. A second channel having a longitudinal axisoriented about parallel to a longitudinal axis of the array of magnetictransducers is present for inducing tenting of a moving magneticrecording tape above the array of magnetic transducers. The firstchannel and the second channel are positioned on opposite sides of thearray of magnetic transducers.

A method according to one embodiment includes forming a channel in atape bearing surface of a module. The channel is formed to have alongitudinal axis about parallel to a longitudinal axis of an array ofmagnetic transducers. The channel is formed proximate to the array ofmagnetic transducers for inducing tenting of a moving magnetic recordingtape above the array of magnetic transducers.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2A illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2B is a tape bearing surface view taken from Line 2B of FIG. 2A.

FIG. 2C is a detailed view taken from Circle 2C of FIG. 2B.

FIG. 2D is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIGS. 8A-8C are schematics depicting the principles of tape tenting.

FIG. 9 is a representational diagram of files and indexes stored on amagnetic tape according to one embodiment.

FIG. 10A is a perspective view of a magnetic tape head according to oneembodiment.

FIG. 10B is a cross sectional view of the magnetic tape head of FIG. 10Ataken along line 10B-10B of FIG. 10A.

FIG. 10C is a tape bearing surface view of the magnetic tape head ofFIG. 10A.

FIGS. 11A-11E are partial side views of a channel along the longitudinalaxis thereof according to various embodiments.

FIG. 12 is a perspective view of a magnetic tape head according to oneembodiment.

FIG. 13 is a flowchart of a method according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general embodiment, an apparatus includes a module having a tapebearing surface, an array of magnetic transducers, and a channel in thetape bearing surface. The channel has a longitudinal axis oriented aboutparallel to a longitudinal axis of the array of magnetic transducers forinducing tenting of a moving magnetic recording tape above the array ofmagnetic transducers.

In another general embodiment, an apparatus includes a module having atape bearing surface and an array of magnetic transducers. A firstchannel having a longitudinal axis oriented about parallel to alongitudinal axis of the array of magnetic transducers is present forinducing tenting of a moving magnetic recording tape above the array ofmagnetic transducers. A second channel having a longitudinal axisoriented about parallel to a longitudinal axis of the array of magnetictransducers is present for inducing tenting of a moving magneticrecording tape above the array of magnetic transducers. The firstchannel and the second channel are positioned on opposite sides of thearray of magnetic transducers.

In another general embodiment, a method includes forming a channel in atape bearing surface of a module. The channel is formed to have alongitudinal axis about parallel to a longitudinal axis of an array ofmagnetic transducers. The channel is formed proximate to the array ofmagnetic transducers for inducing tenting of a moving magnetic recordingtape above the array of magnetic transducers.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may include at least oneservo channel and at least one data channel, each of which include dataflow processing logic configured to process and/or store information tobe written to and/or read from the tape 122. The controller 128 mayoperate under logic known in the art, as well as any logic disclosedherein, and thus may be considered as a processor for any of thedescriptions of tape drives included herein, in various embodiments. Thecontroller 128 may be coupled to a memory 136 of any known type, whichmay store instructions executable by the controller 128. Moreover, thecontroller 128 may be configured and/or programmable to perform orcontrol some or all of the methodology presented herein. Thus, thecontroller 128 may be considered to be configured to perform variousoperations by way of logic programmed into one or more chips, modules,and/or blocks; software, firmware, and/or other instructions beingavailable to one or more processors; etc., and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (internal or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or another device.

By way of example, FIG. 2A illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B may be made of the sameor similar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2B illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2B of FIG. 2A. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 32 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2B on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2C depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2B. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2C, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2A and 2B-2C together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2D shows a partial tape bearing surface view of complementarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeably. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (-),cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor 234 forsensing a data track on a magnetic medium, a second shield 238 typicallyof a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known aspermalloy), first and second writer pole tips 228, 230, and a coil (notshown). The sensor may be of any known type, including those based onMR, GMR, AMR, tunneling magnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used LTO tape head spacing. The open space between themodules 302, 304, 306 can still be set to approximately 0.5 to 0.6 mm,which in some embodiments is ideal for stabilizing tape motion over thesecond module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore, a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads. Moreover, unless otherwisespecified, processes and materials of types known in the art may beadapted for use in various embodiments in conformance with the teachingsherein, as would become apparent to one skilled in the art upon readingthe present disclosure.

As a tape is run over a module, it is preferred that the tape passessufficiently close to magnetic transducers on the module such thatreading and/or writing is efficiently performed, e.g., with a low errorrate. According to some approaches, tape tenting may be used to ensurethe tape passes sufficiently close to the portion of the module havingthe magnetic transducers. To better understand this process, FIGS. 8A-8Cillustrate the principles of tape tenting. FIG. 8A shows a module 800having an upper tape bearing surface 802 extending between oppositeedges 804, 806. A stationary tape 808 is shown wrapping around the edges804, 806. As shown, the bending stiffness of the tape 808 lifts the tapeoff of the tape bearing surface 802. Tape tension tends to flatten thetape profile, as shown in FIG. 8A. Where tape tension is minimal, thecurvature of the tape is more parabolic than shown.

FIG. 8B depicts the tape 808 in motion. The leading edge, i.e., thefirst edge the tape encounters when moving, may serve to skive air fromthe tape, thereby creating a subambient air pressure between the tape808 and the tape bearing surface 802. In FIG. 8B, the leading edge isthe left edge and the right edge is the trailing edge when the tape ismoving left to right. As a result, atmospheric pressure above the tapeurges the tape toward the tape bearing surface 802, thereby creatingtape tenting proximate each of the edges. The tape bending stiffnessresists the effect of the atmospheric pressure, thereby causing the tapetenting proximate both the leading and trailing edges. Modeling predictsthat the two tents are very similar in shape.

FIG. 8C depicts how the subambient pressure urges the tape 808 towardthe tape bearing surface 802 even when a trailing guide 810 ispositioned above the plane of the tape bearing surface.

It follows that tape tenting may be used to direct the path of a tape asit passes over a module. As previously mentioned, tape tenting may beused to ensure the tape passes sufficiently close to the portion of themodule having the magnetic transducers, preferably such that readingand/or writing is efficiently performed, e.g., with a low error rate.

Magnetic tapes may be stored in tape cartridges that are, in turn,stored at storage slots or the like inside a data storage library. Thetape cartridges may be stored in the library such that they areaccessible for physical retrieval. In addition to magnetic tapes andtape cartridges, data storage libraries may include data storage drivesthat store data to, and/or retrieve data from, the magnetic tapes.Moreover, tape libraries and the components included therein mayimplement a file system which enables access to tape and data stored onthe tape.

File systems may be used to control how data is stored in, and retrievedfrom, memory. Thus, a file system may include the processes and datastructures that an operating system uses to keep track of files inmemory, e.g., the way the files are organized in memory. Linear TapeFile System (LTFS) is an exemplary format of a file system that may beimplemented in a given library in order to enables access to complianttapes. It should be appreciated that various embodiments herein can beimplemented with a wide range of file system formats, including forexample IBM Spectrum Archive Library Edition (LTFS LE). However, toprovide a context, and solely to assist the reader, some of theembodiments below may be described with reference to LTFS which is atype of file system format. This has been done by way of example only,and should not be deemed limiting on the invention defined in theclaims.

A tape cartridge may be “loaded” by inserting the cartridge into thetape drive, and the tape cartridge may be “unloaded” by removing thetape cartridge from the tape drive. Once loaded in a tape drive, thetape in the cartridge may be “threaded” through the drive by physicallypulling the tape (the magnetic recording portion) from the tapecartridge, and passing it above a magnetic head of a tape drive.Furthermore, the tape may be attached on a take-up reel (e.g., see 121of FIG. 1A above) to move the tape over the magnetic head.

Once threaded in the tape drive, the tape in the cartridge may be“mounted” by reading metadata on a tape and bringing the tape into astate where the LTFS is able to use the tape as a constituent componentof a file system. Moreover, in order to “unmount” a tape, metadata ispreferably first written on the tape (e.g., as an index), after whichthe tape may be removed from the state where the LTFS is allowed to usethe tape as a constituent component of a file system. Finally, to“unthread” the tape, the tape is unattached from the take-up reel and isphysically placed back into the inside of a tape cartridge again. Thecartridge may remain loaded in the tape drive even after the tape hasbeen unthreaded, e.g., waiting for another read and/or write request.However, in other instances, the tape cartridge may be unloaded from thetape drive upon the tape being unthreaded, e.g., as described above.

Magnetic tape is a sequential access medium. Thus, new data is writtento the tape by appending the data at the end of previously written data.It follows that when data is recorded in a tape having only onepartition, metadata (e.g., allocation information) is continuouslyappended to an end of the previously written data as it frequentlyupdates and is accordingly rewritten to tape. As a result, the rearmostinformation is read when a tape is first mounted in order to access themost recent copy of the metadata corresponding to the tape. However,this introduces a considerable amount of delay in the process ofmounting a given tape.

To overcome this delay caused by single partition tape mediums, the LTFSformat includes a tape that is divided into two partitions, whichinclude an index partition and a data partition. The index partition maybe configured to record metadata (meta information), e.g., such as fileallocation information (Index), while the data partition may beconfigured to record the body of the data, e.g., the data itself.

Looking to FIG. 9, a magnetic tape 900 having an index partition 902 anda data partition 904 is illustrated according to one embodiment. Asshown, data files and indexes are stored on the tape. The LTFS formatallows for index information to be recorded in the index partition 902at the beginning of tape 906, as would be appreciated by one skilled inthe art upon reading the present description.

As index information is updated, it preferably overwrites the previousversion of the index information, thereby allowing the currently updatedindex information to be accessible at the beginning of tape in the indexpartition. According to the specific example illustrated in FIG. 9, amost recent version of metadata Index 3 is recorded in the indexpartition 902 at the beginning of the tape 906. Conversely, all threeversion of metadata Index 1, Index 2, Index 3 as well as data File A,File B, File C, File D are recorded in the data partition 904 of thetape. Although Index 1 and Index 2 are old (e.g., outdated) indexes,because information is written to tape by appending it to the end of thepreviously written data as described above, these old indexes Index 1,Index 2 remain stored on the tape 900 in the data partition 904 withoutbeing overwritten.

The metadata may be updated in the index partition 902 and/or the datapartition 904 differently depending on the desired embodiment. Accordingto some embodiments, the metadata of the index partition 902 may beupdated in response to the tape being unmounted, e.g., such that theindex may be read from the index partition when that tape is mountedagain. The metadata may also be written in the data partition 902 so thetape may be mounted using the metadata recorded in the data partition902, e.g., as a backup option.

According to one example, which is no way intended to limit theinvention, LTFS LE may be used to provide the functionality of writingan index in the data partition when a user explicitly instructs thesystem to do so, or at a time designated by a predetermined period whichmay be set by the user, e.g., such that data loss in the event of suddenpower stoppage can be mitigated.

As described above in FIGS. 8A-8C, tape tenting allows the tape to passsufficiently close to the portion of the module having the magnetictransducers with a low error rate. It would be desirable to create tapetenting near the magnetic transducers without having to depend onproximity to an edge of the module to achieve the desired tenting abovethe transducers.

Embodiments described herein include an apparatus to reduce friction andscratching susceptibility in the sensor region of the head with tapetenting induced by novel means that induces tape tenting above themagnetic transducers but does not use an edge of the module as describedin FIGS. 8A-8C.

FIGS. 10A-10C depict an apparatus 1000, in accordance with oneembodiment. As an option, the present apparatus 1000 may be implementedin conjunction with features from any other embodiment listed herein,such as those described with reference to the other FIGS. Of course,however, such apparatus 1000 and others presented herein may be used invarious applications and/or in permutations which may or may not bespecifically described in the illustrative embodiments listed herein.Further, the apparatus 1000 presented herein may be used in any desiredenvironment.

According to one embodiment as shown in a perspective view in FIG. 10A,an apparatus 1000 includes a module 1001 having a tape bearing surface1002, an array 1006 of magnetic transducers 1004, and a channel 1008 inthe tape bearing surface 1002. The channel 1008 has a longitudinal axis1014 that may be oriented about parallel to a longitudinal axis 1016 ofthe array 1006 of magnetic transducers 1004. In various embodiments, thetape bearing surface 1002 of the apparatus 1000 may be planar.

In some embodiments, the array 1006 of magnetic transducers 1004 may bewrite transducers. In other embodiments, the array 1006 of magnetictransducers 1004 may be read transducers.

Looking to the side view of the module 1001 in FIG. 10B, the channel1008 may induce tenting 1018 of a moving magnetic recording tape 1010above the array of magnetic transducers 1004. As the tape 1010 is inmotion, as shown in FIG. 10B, the relative movement of the tape 1010over the channel 1008 entrains air from the channel 1008, creating asub-ambient air pressure in the channel 1008. As a result, atmosphericpressure above the tape urges the tape 1010 into the interior of thechannel 1008, thereby creating tape tenting 1018 proximate to thechannel edge 1020, and above the array 1006 of magnetic transducers1004. This phenomenon occurs when the tape is moving in either tapetravel direction 1012.

In one embodiment, the array 1006 of magnetic transducers 1004 may bepositioned about under a peak (highest point) of a tent 1018 formed bythe moving magnetic recording tape 1010. In another embodiment, thearray 1006 of magnetic transducers 1004 may be positioned between thepeak and the channel 1008. In yet another embodiment, the array 1006 ofmagnetic transducers 1004 may be positioned on an opposite side of thepeak as the channel.

FIG. 10C depicts a top view of the module 1001 that shows thelongitudinal axis of the channel 1008 may be oriented about parallel tothe array 1006 of magnetic transducers 1004 where the direction 1012 oftape movement may pass from top to bottom of the figure, according toone embodiment. In various embodiments, the channel 1008 is preferablypositioned such that a tape 1010 moving over the module covers theentire channel 1008 in all reading and writing positions. As shown inFIG. 10C, the first width w_(ch1) of the channel 1008 along thelongitudinal axis thereof may be wider than a width w_(a) of the array1006 of magnetic transducers 1004 along the longitudinal axis thereof.

In some embodiments, the first width w_(ch1) of the channel may be lessthan a width w_(t) of a tape 1010 for which the apparatus 1000 may bedesigned, e.g., as shown in FIG. 10C. Preferably, the first widthw_(ch1) of the channel at least approximately the width of a data bandfor which the module is designed.

In some approaches, the first width w_(ch1) of the channel is less thana distance between servo sensors of the module, e.g., slightly less(e.g., the outer edges of the channel are within about 150 microns ofthe servo sensor closest thereto). Preferably, the first width w_(ch1)of the channel is greater than the width of the span of data transducersin the array. Note that the array described herein may refer to only thedata transducers, or may refer to the data and servo transducers. Inanother approach, the first width w_(ch1) of the channel is slightlywider than the distance between the servo sensors, e.g., up to about 300microns wider.

In various embodiments, a second width w_(ch2) of the channel 1008 inthe direction 1012 of tape motion may in part determine the extent oftenting of the moving magnetic tape 1010 as it passes over the channeledge 1020 of the channel 1008 (the trailing edge as the tape passes fromtop to bottom). In various embodiments, the extent of bending of thetape 1010 from the edge 1020 of the channel 1008 nearest the array 1006may also depend on expected media parameters. Thus, the second widthw_(ch2) of the channel 1008 may be determined by parameters of themagnetic tape to be used with the tape head, for example, bendingstiffness, etc.

In some embodiments, the second width w_(ch2) of the channel 1008 in thedirection 1012 of tape motion may be in a range of about 5 μm to about100 μm. In one embodiment, the second width w_(ch2) of the channel 1008may be preferably about 25 μm.

In one embodiment of apparatus 1000 as shown in FIG. 10C, a distance dbetween the channel 1008 and the array 1006 of magnetic transducers 1004along the tape bearing surface 1002 in a direction 1012 of tape travelmay be in a range of about 5 μm to about 50 μm, but the distance d couldbe higher or lower, depending on the desired location of the tenting.Looking back to FIG. 10B, the value of the distance d (FIG. 10C) may beselected to ensure that the tenting 1018 of the moving tape 1010 inducedby bending of the tape at the edge 1020 of the channel 1008 occurs abovethe array 1006 of magnetic transducers 1004. For example, but notlimited to these examples, if the tape is relatively stiff, then thechannel may induce a wider tent, thereby allowing the distance betweenthe channel and the array of magnetic transducers to be made larger. Ifthe tape is less stiff, then the channel may induce a narrower tent,whereby the distance between the channel and the array of magnetictransducers may be made smaller.

In some embodiments, the tenting 1018 of the moving magnetic tape 1010induced by the tape moving over the channel 1008 may increase separationbetween the tape 1010 and the tape bearing surface 1002 of the module1001, and particularly, increase separation between potential defectslodged in the tape 1010 and the tape bearing surface 1002. Furthermore,a negative curvature at the top of the tent 1018, as shown in FIG. 10B,may provide additional benefit such that the curvature may cause defectsin the tape 1010 to retract from the tape bearing surface 1002 of themodule 1001. In contrast, defects in media running over conventionalheads tend to protrude from the tape and approach the tape bearingsurface as the tape bends slightly into the recessed gap of the magnetictransducer and thereby increase the incidence of shorting when thedefects drag across the tunnel barrier region.

In some approaches of the apparatus, a media facing side of the array ofmagnetic transducers may be recessed from the tape bearing surface.

One embodiment of apparatus 1000 may include a drive mechanism such as amotor or other known mechanism for passing a magnetic medium over themodule 1001 and a controller electrically coupled to the array ofmagnetic transducers. For example, the motor or other known mechanismmay drive a tape supply cartridge, e.g., tape supply cartridge 120 ofFIG. 1A, and a take-up reel, e.g., take-up reel 121 also of FIG. 1A, ofa drive in which the block is implemented in, to move the tape mediaover the block and/or other components of the drive.

According to various embodiments, the channel may have a middle regionextending along the longitudinal axis of the channel, where thelongitudinal axis extends between opposite edges of the channel that arefarthest apart. Moreover, the middle region may be more recessed intothe tape bearing surface than the edges. In one embodiment as shown inFIG. 11A, a cross-sectional profile of the channel 1108 may be arcuate,e.g., having a shape of a section of a circle. As shown, the channel1108 may have a middle region 1130 extending along the longitudinal axis1014 of the channel 1108 between opposite edges 1132, 1134 of thechannel 1108. The middle region 1130 may be more recessed into the tapebearing surface 1002 than the edges 1132, 1134. In some embodiments, thetape may contact the bottom of the channel near the edges therebyhelping smooth the edges to the beveled region.

In another embodiment as shown in FIG. 11B, a cross-sectional profile ofthe channel 1118 may have a shape with a middle section of similarrecession extended to curved opposite ends.

In yet another embodiment as shown in FIG. 11C, a cross-sectionalprofile of the channel 1128 may have a triangular shape with a middlesection that may be more recessed than the opposite ends.

In yet another embodiment as shown in FIG. 11D, a cross-sectionalprofile of the channel 1138 may have a shape with a middle section ofsimilar recession therealong between straight opposite ends.

In yet another embodiment as shown in FIG. 11E, a cross-sectionalprofile of the channel 1148 may have a shape with a middle section ofsimilar recession therealong between vertical opposite sides.

The illustrations in FIGS. 11A-11E may represent a selection of possibleembodiments and are not meant to be limiting to the embodimentsdescribed herein. Rather, the profile of the channel may be any suitableshape that would become apparent to one skilled in the art upon readingthe present descriptions.

In various embodiments, as shown for example in FIG. 11A, a depth ofrecession r of the channel 1108 from the plane 1104 of the tape bearingsurface 1002 to the furthest recessed portion, for example the middleregion 1130, of the channel 1008 may be in a range of about 2 μm toabout 5 μm or more.

FIG. 12 depicts an apparatus 1200, in accordance with one embodiment. Asan option, the present apparatus 1200 may be implemented in conjunctionwith features from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, suchapparatus 1200 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 1200 presented herein may be used in any desired environment.

In one embodiment as shown in FIG. 12, an apparatus 1200 includes amodule 1201 having a tape bearing surface 1002, an array 1206 ofmagnetic transducers 1204, a first channel 1208 having a longitudinalaxis oriented about parallel to a longitudinal axis of the array 1206 ofmagnetic transducers 1204. for inducing tenting of a moving magneticrecording tape above the array of magnetic transducers. Moreover, theapparatus 1200 includes a second channel 1210 having a longitudinal axisoriented about parallel to a longitudinal axis of the array 1206 ofmagnetic transducers 1204 for inducing tenting of a moving magneticrecording tape above the array of magnetic transducers. According to anembodiment of apparatus 1200, the first channel 1208 and the secondchannel 1210 may be positioned on opposite sides of the array 1206 oftransducers 1204.

FIG. 13 depicts a method 1300 for forming a channel in a tape bearingsurface of a module, in accordance with one embodiment. As an option,the present method 1300 may be implemented in conjunction with featuresfrom any other embodiment listed herein, such as those described withreference to the other FIGS. Of course, however, such method 1300 andothers presented herein may be used in various applications and/or inpermutations which may or may not be specifically described in theillustrative embodiments listed herein. Further, the method 1300presented herein may be used in any desired environment.

In one embodiment as shown in FIG. 13, a method 1300 begins with step1302 involving forming a channel in a tape bearing surface of a module,where the channel may be formed having a longitudinal axis aboutparallel to a longitudinal axis of an array of magnetic transducers.Moreover, the channel may be formed proximate to the array of magnetictransducers for inducing tenting of a moving magnetic recording tapeabove the array of transducers.

In one embodiment of step 1302 of method 1300, the channel may be formedas a shape that has a middle region extending along the longitudinalaxis of the channel between opposite edges of the channel, where themiddle region may be more recessed into the tape bearing surface thanthe edges. Any suitable technique for forming the channel may be used.In some approaches, the channel may be formed by plunge cutting with adiamond circular saw. In other approaches, the channel may be formed bymilling using conventional techniques and further processed using knowntechniques that provide edge blending, for example,micro-opto-mechanical (MOEM) optical processing, ion etching, etc. Inyet other approaches, laser ablation may be used.

In various embodiments of step 1302 of method 1300 the width of thechannel along the longitudinal axis may be in a range of about 5 μm toabout 100 μm. In a preferred embodiment of method 1300, the width of thechannel along the longitudinal axis may be about 25 μm.

In some embodiments of step 1302 of method 1300, a depth of recession ofthe channel may be in a range of about 2 μm to about 5 μm or more.

In some embodiment of step 1302 of method 1300, a distance between thechannel and the array of magnetic transducers along the tape bearingsurface in a direction of tape travel may be in a range of about 5 μm toabout 50 μm, but the distance could be higher or lower, depending onexpected media parameters.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: a module having a tapebearing surface, an array of magnetic transducers, and a channel in thetape bearing surface, the channel having a longitudinal axis orientedabout parallel to a longitudinal axis of the array of magnetictransducers for inducing tenting of a moving magnetic recording tapeabove the array of magnetic transducers, wherein the channel has amiddle region extending along the longitudinal axis of the channelbetween opposite edges of the channel, wherein the middle region is morerecessed into the tape bearing surface than the edges.
 2. An apparatusas recited in claim 1, wherein a first width of the channel along thelongitudinal axis thereof is wider than a width of the array of magnetictransducers along a longitudinal axis of the array of magnetictransducers.
 3. An apparatus as recited in claim 2, wherein the firstwidth of the channel along the longitudinal axis thereof is less than awidth of a tape for which the apparatus is designed.
 4. An apparatus asrecited in claim 1, wherein a second width of the channel in a directionof tape motion is in a range of about 5 microns to about 100 microns. 5.An apparatus as recited in claim 1, wherein a depth of the channel is ina range of about 2 microns to about 5 microns.
 6. An apparatus asrecited in claim 1, wherein a distance between the channel and the arrayof magnetic transducers along the tape bearing surface in a direction oftape travel is in a range of about 5 microns to about 50 microns.
 7. Anapparatus as recited in claim 1, wherein the channel is configured toinduce a sub-ambient pressure in the channel upon a relative movement ofthe moving magnetic recording tape over the channel, thereby resultingin the tenting of the moving magnetic recording tape above the array ofmagnetic transducers.
 8. An apparatus as recited in claim 1, wherein thearray of magnetic transducers is positioned about under a peak of a tentformed by the moving magnetic recording tape.
 9. An apparatus as recitedin claim 1, wherein the tape bearing surface is planar.
 10. An apparatusas recited in claim 1, wherein the array of magnetic transducers is anarray of read transducers.
 11. An apparatus as recited in claim 1,further comprising: a drive mechanism for passing a magnetic medium overthe module; and a controller electrically coupled to the array ofmagnetic transducers.
 12. An apparatus comprising: a module having atape bearing surface, an array of magnetic transducers, and a channel inthe tape bearing surface, the channel having a longitudinal axisoriented about parallel to a longitudinal axis of the array of magnetictransducers for inducing tenting of a moving magnetic recording tapeabove the array of magnetic transducers, wherein the channel is arcuate.13. A method, comprising: forming a channel in a tape bearing surface ofa module, wherein the channel is formed having a longitudinal axis aboutparallel to a longitudinal axis of an array of magnetic transducers,wherein the channel is formed proximate to the array of magnetictransducers for inducing tenting of a moving magnetic recording tapeabove the array of magnetic transducers, wherein the channel is formedas a shape that has a middle region extending along the longitudinalaxis of the channel between opposite edges of the channel, wherein themiddle region is more recessed into the tape bearing surface than endsof the channel adjacent the edges.
 14. A method as recited in claim 13,wherein the channel is formed by milling.
 15. A method as recited inclaim 13, wherein a width of the channel along the longitudinal axis isin a range of about 5 microns to about 100 microns.
 16. A method asrecited in claim 13, wherein a depth of the channel is in a range ofabout 2 microns to about 5 microns.
 17. A method as recited in claim 13,wherein a distance between the channel and the array of magnetictransducers along the tape bearing surface in a direction of tape travelis in a range of about 5 microns to about 50 microns.